The deterioration and preservation of printed cellulosic materials such as books, documents, manuscripts, and works of art on paper is a serious problem throughout the world. Large quantities of these materials have deteriorated to such an extent that only a very few, if any, people can use them; and if so, only under restricted conditions because these materials are embrittled and very fragile. The problem is not limited to isolated instances of the deterioration of individual examples of rare and ancient documents, but alarmingly threatens virtually all portions of archive, library, and museum collections. Up to 40 percent of virtually irreplaceable books and records in major research library collections are so deteriorated that they cannot be read.
Acid-catalyzed hydrolysis of the cellulose during aging, causing up to 95 percent of the deterioration, is considered the most significant cause of deterioration of cellulosic materials. Acid attack causes degradation of cellulose by random schism of the hemi-acetal links between the anhydro-glucose monomers that make up cellulose molecules. This reaction shortens the molecules, and weakens, and embrittles cellulosic material. Acids catalyze this reaction and the presence of hydrogen ions associated with an acidic condition in paper greatly accelerates the rate of deterioration. An acidic condition may result from the way cellulosic materials are manufactured, from storage conditions, or from natural aging. The acidity may come from the use of papermaker's alum in paper making, air pollutants, or the degradation products of the cellulosic material and printing ink mediums. Oxidative and photochemical degradation, and other aging mechanisms have a similarly deleterious effect on cellulosic materials, but cause a lower amount of deterioration.
Most of the present day library collections have been published since the early nineteenth century. Chemical wood pulp fibers, prepared with alum-rosin sizes, not only make up most of the paper in library collections, but contain the seeds of its own destruction. Alum-rosin sizing is the primary source of acidity in paper; and this acidity is the primary cause of paper deterioration. Conventional wood pulping processes may also degrade and/or oxidize the cellulose fibers, or may not remove all unstable non-cellulosic materials from the wood.
In general, library collections are printed on acidic paper with poor aging characteristics. In terms of their lifetimes, many library books have reached old age or are rapidly approaching it. My studies indicate that almost all books published between 1900 and 1960 cannot be effectively rebound after they are 60 years old, and will be unable to resist even mild use when they are 100 years old. The urgency of the situation is compounded by acidic and oxidizing air pollutants, such as sulfur and nitrogen oxides, which accelerate the deterioration of ordinary paper and even cause otherwise permanent paper to deteriorate, embrittle, and discolor.
This appalling deterioration of the records of our society is not limited to library collections but is equally true for the collections of archives and museums, and the collections of private individuals.